Tuya-Convert might not be possible for this device since the template was added (2020-12-26). All new Tuya devices have firmware preventing flash but it is still possible to Tuya-Convert old stock devices without connecting them to the Tuya app.
Since EG-EW003MC is a Tuya based device, Tuya-Convert flash is possible.
This method does’t need any wiring.
“Power monitoring already working. Based on Teckin (52) plug but with the button connected on GPIO 3 and no additional LED on that pin. Red LED is hardwired with the relay. BL0937 chip as power meter. Uses TYWE2S Tuya ESP8265 MCU. I strongly recommend NOT loading more than 10 A or 2300 W (relay looks like a bit wimpy).
To open it, just pry the socket out. Then desolder the female output contacts and remove the protective white plastic. Then desolder the male prongs. Tip: twist them using a pliers while the tin is melted to ensure the connection is broken. To remove the board, either use a long nose pliers and grab it at the ground terminal holes or push it from behind using a thin screwdriver. Take care not to damage any tracks (had to fix three after that).